US005892107A
United States Patent [19]
[11]
Farone et al.
[45] Date of Patent:
[54]
METHOD FOR THE PRODUCTION OF LEVULINIC ACID
[75]
Inventors: William A. Farone, Irvine; John E. Cuzens, Santa Ana, both of Calif.
Patent Number:
5,892,107 Apr. 6, 1999
Furfural as a neW decompotition product of glucose solution under oxygen atmosphere, Letters to the Editor, J. Pharm.
Pharmac., 1978, 30, p. 668.
[73] Assignee: Arkenol, Inc., Mission Viejo, Calif.
[21] Appl. No.: 747,441 [22]
Filed:
NOV. 8, 1996
[51] [52]
Int. Cl.6 .......................... .. C07C 51/00; C07C 27/00 US. Cl. ........................ .. 562/515; 549/489; 549/508;
[58]
Field of Search ............................................. .. 562/515
549/326; 560/174 [56]
References Cited US. PATENT DOCUMENTS 2,813,900
11/1957 Dunlop et al. ........................ .. 562/515
2,840,605 3,701,789
10/1972 6/1958
4,236,021 4,897,497
11/1980 Hsu et al. ............................. .. 560/174 1/1990 Fitzpatrick ............................ .. 549/489
Leonard Ramos-Rodriguez ............. .. ................ .. 562/515
FOREIGN PATENT DOCUMENTS 619795
4/1961
Italy .
OTHER PUBLICATIONS
The hydrogenation of 2—furaldehyde and its derivatives. G.
Natta, R. Rigamonti and E. Beati, 23, 117—23 (1941), Chemical Abstracts, vol. 35, pp. 5488—5489.
Levulinic acid. Wendell W. Moyer (to A.E. Staley Mfg. Co.). US. 2,270,328, Jan. 20., 1942 10—Organic Chemistry, p. 3190.
Levulinic acid. Georg Scheuing and Wilhelm KonZ (vested in the Alien Property Custodian). US. 2,305,738, Dec. 22., 1942 Chemical Abstracts, vol. 37, p. 3252. Levulinic acid. Walter N. HaWorth and Leslie F. Wiggins.
Practical Organic Chemistry including Qualitative Organic Analysis by Arthur I. Vogel, Third Edition, 1962, John Wiley & Sons, Inc., NeW York, NY, pp. 461—463.
Reagents for Organic Synthesis, Louis F. Fieser, 1967, John Wiley and Sons, Inc., NeW York, NY, pp. 564—566. The Journal of the American Chemical Society, vol. LII, Sep.—Dec., 1930 by Arthur B. Lamb, “Levulinic Acid and its Esters” by Peter P.T. Sah and Shao—Yuan Ma, Dec. 18, 1930, vol. 52, pp. 4880—4883. Levulinic acid recovery. Alexander D. Macallum (to BL du Pont de Nemours & Co.). US. 2,257,389, Sep. 30., 1941 Chemical Abstracts, vol. 36, p. 99. USPTO CNIDR, US. Patent 4,236,021, Nov. 25, 1980, Abstract for “Process for the manufacture of levulinic acid and esters”. Levulinic Acid as a Basic Chemical RaW Material, Reid H.
Leonard, Industrial and Engineering Chemistry, vol. 48, No. 8, Aug. 1956, pp. 1330—1341. Effect of heat on aqueous solutions of sucrose and other
carbohydrates. R. Montgomery and LE Wiggins, J. Soc. Chem. Ind. 66, 31—2 (1947); Chemical Abstracts, vol. 41, C01. 4025. Interpretation of some reactions in the carbohydrate ?eld in terms of consecutive electron displacement. Horace S.
Isbell. J. Research Natl. Bur. Standards 32, 45—59 (1944); Chemical Abstracts, vol. 38, C01. 2319. Thermochemical Pretreatment of Lignocellulose to Enhance Methane Fermentation: I. Monosaccharide and Furfurals
Hydrothermal Decomposition and Product Formation Rates. K. Baush and P. McCarty, Biotechnology and Bioengineer ing, vol. 31, pp. 50—61 (1988). Takahashi, J. Agr. Chem. Soc. Japan, vol. 20, pp. 553—556, 1944.
Brit. 583,533, Dec. 20, 1946, Chemical Abstracts, 1947, p. 3123.
Derivatives of valerolactone, 1,4—pentanediol, and 1,4—bis (2—cyanoethoXy) pentane. Robert V. Christian, J. Am. Chem. Soc. 69, 1961—3 (1947), 10—Organic Chemistry, pp. 6873—6874.
Primary Examiner—Bernard DentZ Attorney, Agent, or Firm—Knobbe, Martens Olson and Bear LLP
[57]
ABSTRACT
Levulinic acid. HolZhydrolyse Akt.—Ges. Ger. 700,643, Nov.
28, 1940, 10—Organic Chemistry, p. 6981.
A method of producing dehydration products from one or
Levulinic acid. HolZhydrolyse Akt.—Ges. Ger. 705,578, Mar. 27, 1941, Chemical Abstracts, vol. 36, p. 2079.
more 5 -carbon or 6-carbon sugars includes reacting said one or more sugars at 40°—240 ° C. for 1 to 96 hours in the
34, p. 7299.
presence of 10—90% sulfuric acid, separating the reaction products, and recovering levulinic acid. The sugars can be generated from strong acid hydrolysis of biomass, such as
Organic Chemistry by Paul Karrer, Second English Edition,
rice straW, paper, cotton and other cellulosic materials.
Levulinic acid. Alva Thompson (to Corn Products Re?ning Co.). US. 2,206,311, Jul. 2., 1940 Chemical Abstracts, vol.
1946, Elsevier Publishing Company, Inc., NeW York, Furan p. 737.
32 Claims, 2 Drawing Sheets
U.S. Patent
Apr. 6, 1999
Sheet 1 of2
5,892,107
PRODUCT FLOW DIAGRAM
IE EH-
REAcToR 10o DEC 0
24 Hrs_ 2
4
_E|_- HOLDING
E» FILTER 5 @H'
TANK 7
I?
En CHROM [5+ SEPARATOR —
|2—7_\ HYDROGENATOR
26
*@ ' @
LEVULINIC 5Z1 REACTON
CONCENTRATION 2s
DRYER
12 14
IIEI
E]
A?‘ |28Z29|
5?
FURFURAL CONCENTRATION
' @]
_
PURIFICATION 19
IéTTI
‘
‘IE
SULFURIC ACID
CONCENTRATION 15
R FIG. 1
U.S. Patent
Apr. 6, 1999
Sheet 2 012
5,892,107
CHROMATOGRAPHY OF LEVULINIC ACID 2500 1
Z 9 |_
SULFURIC
2000
ACID /
:2
/
E 1500
.
24 HOURS AT 1000
L|_l
D!
g 1000
'2
G
a:
INTERNAL 500
STANDARD
/
0 0.00
LEVULINIC ACID
/L 2.00
4.00
?y 6.00
8.00
TIME (min.)
FIG. 2
10.00
12.00
14.00
5,892,107 1
2
METHOD FOR THE PRODUCTION OF LEVULINIC ACID
Walter N. HaWorth and Leslie F. Wiggins, British Patent No. 583,533. Sulfuric acid has been used as the acid source in
dehydration reaction of bran, the here the reported product is furfural, rather than levulinic acid. See Paul Karrer,
FIELD OF THE INVENTION
“Organic Chemistry,” 2nd ed, Elsevier Publishing Co, Inc., The present invention relates to a method of producing levulinic acid from sugars in the presence of concentrated acid. In addition, the invention relates to a method for
NeW York 1946, p.737.
producing methytetrahydrofuran from the levulinic acid thus
about tWo-thirds the theoretical yield can be attained in the presence of dilute HCL. Interestingly, substantially the same yields Were obtained from cellulose in Douglas ?r saWdust. See Reid H. Leonard, supra. Thus, it appears possible to utiliZe cellulosic materials to produce sufficient quantities of
obtained. These novel methods can utilize Waste biomass as
the starting material for the levulinic acid and its numerous
The theoretical yield of levulinic acid from a hexose is
64.5%. The literature in the art, hoWever, indicates that only 10
derivatives, thus adding to the economic viability of the invention.
levulinic acid to be used as a basic raW chemical material.
BACKGROUND OF THE INVENTION
15
Levulinic acid is a major product of the controlled deg radation of sugars by acid hydrolysis. Although levulinic acid has been knoWn since the 1870’s, it has never attained much commercial signi?cance. One of the reasons for its sloW development is the cost of the raW materials for synthesis. Another reason is the loW yields of levulinic acid obtained from most synthetic methods. These loW yields are
chemical are numerous. For example, esters of levulinic acid are used for ?avoring, and some have been reported to be 20
largely due to the inherent physical properties of levulinic acid Which do not alloW for its facile recovery. Moreover, the
production of levulinic acid has had high associated equip ment costs. Given these factors, therefore, the production of
25
levulinic acid has not appeared to be commercially feasible.
Despite the inherent problems in the production of levulinic acid, hoWever, the reactive nature of levulinic acid makes it an ideal intermediate leading to the production of numerous useful derivatives. Levulinic acid, therefore, is
30
Leonard, “Levulinic Acid as a Basic Chemical RaW 35
The formation of levulinic acid from loW-cost cellulosic material could, hoWever, overcome one of the major dif? 40
Moreover, substitution of levulinic acid for a portion of
the acetyl groups in vinyl acetate-containing resins and cellulose acetate has been shoWn to yield materials of
increased strength. The ot-angelica lactones, one of the simplest products to be made from levulinic acid, can also 50
be converted to a series of pseudolevulinic acid derivatives and has also been reported to be a means of obtaining 3-chloro-levulinic acid. Reduction products of levulinic acid are also important. It
55
tures above 200° C. yields substantial amounts of 1,4 pentanediol, and smaller amounts of
has been reported that catalytic hydrogenation at tempera ot-methyltetrahydrofuran, and 1-pentanol. See Reid H. Leonard; G. Natta, R. Rigamonti and E. Beati, “The Hydro genation of 2-furaldehyde And Its Derivatives,” Chimica e
in a dilute acid solution. See P. T. Sah and S. Y. Ma,
“Levulinic Acid And Its Esters,” J. Amer Chem. Soc., 52:4880 (1930); and L. Fieser and M. Fieser, “Reagents for 60
564—66.
Industria (Italy) 23, 117—23 (1941). In all, the exceptional reactivity of levulinic acid and its lactones coupled With its availability from Waste biomass
In the literature concerning production of levulinic acid
provide an ideal set of conditions for the use of levulinic acid
from sugars, hoWever, generally HCl is used as the acid source in the dehydration reaction of sugars. See L. Fieser
and M. Fieser, supra.; Alva Thompson, US. Pat. No. 2,206, 311; Wendell W. Moyer, US. Pat. No. 2,270,328; Georg Scheuing and Wilhelm KonZ, US. Pat. No. 2,305,738;
acid) is formed together With some [3-angelicalactone (y lactone of 4-hydroxy-2-pentenoic acid). Various heterocy
analgesic agents. 45
glucose and other sugars by the action of boiling the sugars
Organic Synthesis,” John Wiley and Sons, Inc. 1967, p.
4-amino derivatives of levulinic acid readily forms lactams and 5-methylpyrrolidones, While the amides upon hydroge nation of the keto group, also form 5-methylpyrrolidones. Upon distillation, dehydration of levulinic acid occurs and
clic compound are also derived from levulinic acid. Some of these are pyrones, dioxanes, a coumarin, and thiaZocines, Which have been proposed for use as bacteriostatic and
the supply of sugars from cellulose-containing plant biomass is immense and replenishable. Most plants contain cellulose in their cell Wall. For example, cotton is 90% cellulose. Furthermore, it has been estimated that roughly 75% of the approximate 24 million tons of biomass generated on cultivated lands and grasslands is Waste. This cellulose that is derived from plant biomass could be a suitable source of sugars to be used in the process of obtaining levulinic acid. Thus, the conversion of such Waste material into a useful chemical, such as levulinic acid, Would be desirable. Sugars are converted to levulinic acid essentially by a process of dehydration and cleavage of a mole of formic acid. See Reid H. Leonard, supra. The literature in the art suggest that levulinic acid can be formed quite readily from
These include the peroxide, methyl vinyl ketone, and succinic, malonic, and acetoacrylic acids. These derivatives
ot-angelica lactone (y-lactone of 4-hydroxy-3-pentenoic
culties encountered in other synthetic processes. By starting production of levulinic can be greatly reduced. Moreover,
biologically active, materials. Also alkyl metal halides react With levulinate esters to yield a series of y-substituted y-valerolactones, some of Which may be used for perfumes and ?avors. Oxidation products of levulinic acid are also knoWn.
in liquid-liquid extractions of hydrocarbons. In addition, the
Material,” Industrial and Engineering Chemistry, Vol. 48,
With Waste biomass the cost of the starting material for
used as plasticiZer. Reaction of levulinic acid With carbonyl reagents also can yield numerous derivatives, many of Which are hydraZones and semicarbaZones. These deriva tives are of interest for conversion into pyridaZiones and for the preparation of soluble derivatives of insoluble, but
have been postulated to be of use in foods, and as solvents
desirable as a basic chemical raW material. See R. H.
p.1331—41 (1956).
If a loW-cost production of levulinic acid could be achieved, such as the formation of levulinic acid from loW-cost cellulosic material, the useful derivatives of this
as a basic chemical raW material. Thus, there exists a need 65
to be able to produce levulinic acid. Moreover, it Would be most desirable to be able to produce levulinic acid in an
economically viable and environmentally safe process.
5,892,107 3
4
SUMMARY OF THE INVENTION
acid includes: 1) reacting on or more sugars, either 5 -carbon, 6-carbon, or a combination of both, preferably at 40°—240° C. for 1—96 hours in the presence of 10—90% sulfuric acid,
The present invention is directed toward a method of producing levulinic acid and other derivatives, such as
2) separating the reaction products, and 3) recovering
furfural, 5-HMF, succinic acid, maleic acid, fumaric acid, and methyltetrahydrofuran,from sugars.
levulinic acid. This method can also utiliZe plant biomass as a starting material. Additionally, this method can be initiated
One aspect of the present invention is that it can utilize the strong acid hydrolysis method of US. Pat. No. 5,525,777 to
by starting With cellulose and hemicellulose materials. The reaction leading to the production of levulinic acid in this second aspect of the present invention is also preferably
convert biomass to levulinic acid and its derivatives. The
steps of this method include: 1) mixing biomass containing
conducted at 40°—240° C. With a reaction temperature of 80°—200° C. being more preferable, and a reaction tempera
cellulose and hemicellulose With a solution of approximately
ture of 90°—120° C. being the most preferred. The preferred reaction time to produce levulinic acid is betWeen 1—96
25—90% acid, thereby at least partially decrystalliZing the biomass and forming gel that includes a solid and liquid portion, 2) diluting the gel thus obtained to an acid concen
tration of approximately 20—30%, by Weight, and heating the gel to about 80°—100° C., thereby hydrolyZing the cellulose and hemicellulose materials, 3) separating the liquid portion
hours With a reaction time of 4—48 hours being more 15
is 10—90% With a acid concentration of 20—80% being more preferred, While a concentration of 30—40% is the most
from the solid portion, thereby obtaining a ?rst liquid containing a sugar facid mixture, 4) mixing the separated
preferable.
solid portion With a solution of about 25—90% acid, by Weight, until the acid concentration of the resulting gel is
betWeen 20—30%, by Weight, and heating the gel to about 80°—100° C., thereby further hydrolyZing the cellulose and hemicellulose materials remaining in the separated solid portion, 5) separating the resultant liquid portion from the solid portion, thereby obtaining a second liquid containing sugars and acid, 6) combining the ?rst and second liquids, 7)
The production of levulinic acid via the above process also alloWs for recovery of products selected from the group
consisting of furfural, 5-HMF, succinic acid, maleic acid, fumaric acid. These products along With levulinic acid and sulfuric acid can be separated by chromatography, prefer 25
reacting said resulting sugars at 40°—240° C. for 1 to 96
In still another aspect of the present invention, the levulinic acid obtained from either of the tWo method outlined above can be used to form derivative products, such as methyltetrahydrofuran. The steps of this method include:
Additionally, the reaction of the sugars to yield levulinic acid via the strong acid hydrolysis method can be conducted With or Without the addition of additional acid. It is noted that the biomass used in the start of the reaction leading to or cotton materials. Both cellulose and hemicellulose can
1) hydrogenation of the levulinic acid in the presence of H2 and a metal catalyst, 2) separating the reaction products, and 35
drofuran product can be dried after the hydrogenation
reaction, leaving the resulting product in a dry blend form. The preferred metal catalyst to be used in the hydrogenation reaction of levulinic acid is a Ni/Co catalyst. Also, it should be noted that if the levulinic acid is dried subsequent to its
reaction temperature of 90°—120° C. being most preferred. The preferred reaction time leading to the production of levulinic acid is betWeen 1—96 hours With a reaction time of 45
is 7—36 hours. The preferable acid concentration for the production of levulinic acid is 10—90% With a acid concen tration of 20—80% being more preferred, While a concentra tion of 30—40% is the most preferable. It should be noted that
the preferred acid to be used the production of levulinic acid via the strong acid hydrolysis method outlined above is sulfuric acid. The production of levulinic acid via the above process also alloWs for recovery of products selected from the group
production, the resultant product is angelica lactone, due to dehydration of the levulinic acid. In utiliZing any of the above-outlined methods of produc ing levulinic acid, it is preferred that the reaction products be ?ltered prior to separation. Additionally, it is preferable that the ?lter be Washed one or tWo times, and that preferably these Washes are to be combined prior to separation.
Moreover, folloWing separation of the reaction products, levulinic acid can be concentrated to facilitate any further
reaction.
In yet another aspect of the present invention, When utiliZing either of the above-outlined methods, an alcohol 55
consisting of furfural, 5-HMF, succinic acid, maleic acid,
can be added to the reaction mixture subsequent to the
production of levulinic acid. The resultant reaction mixture is preferably run for 1—10 hours at the reaction temperature
fumaric acid. These products along With levulinic acid and sulfuric acid can be separated by chromatography, prefer
of the alcohol. The ?nal reaction mixture can be separated to
ably using an ionic resin. HoWever, it is more preferred that the separation be effectuated using an anionic resin, and most preferably the resins Would also consist of multiple
yield levulinate ester. Preferably the reaction time to produce the ester Would be 2—8 hours With a reaction time of 3—6
hours being most preferred.
chromatographic columns. In another aspect of the present invention, levulinic acid production need not be obtained through the strong acid hydrolysis method, and instead, can be directly converted
3) recovering methyltetrahydrofuran. This hydrogenation reaction can also be conducted in the presence of added ethanol, either in a Wet or in a dry form. The methyltetrahy
also be used as starting material When utiliZing the method outlined above. The reaction leading to the production of levulinic acid is preferably conducted at 40°—240° C. With a reaction tem perature of 80°—200° C. being more preferable, and a
4—48 hours being more preferable. The most preferred reaction time for the production of levulinic acid, hoWever,
ably using an ionic resin. HoWever, it is more preferred that the separation be effectuated using an anionic resin, and most preferably the resins Would also consist of multiple
chromatographic columns.
hours in the presence of the remaining acid, 8) separating the reaction products, and 9) recovering levulinic acid.
levulinic acid can consist of rice straW, Woody plant, paper,
preferable. The most preferred reaction time for the produc tion of levulinic acid, hoWever, is 7—36 hours. The acid concentration preferable for the production of levulinic acid
65
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is schematic vieW of the method of the present invention illustrating in a Product FloW Diagram the steps
from either one of more 5-carbon or 6-carbon sugars. In this
leading to the production of levulinic acid and tetramethy
aspect of the invention, the method of producing levulinic
hydrofuran.
5,892,107 5
6
FIG. 2 represents the relative refractive index of the products as a function of time of elution from the chromato
primarily consist of glucose and xylose With small amounts of the other sugars. HoWever, Where cellulose is used as the starting material in the process, such as that of recycled
graphic system.
paper, the exclusive product is glucose. Additionally, in
DETAILED DESCRIPTION OF THE INVENTION Introduction Recently, a successful process has been discovered that
provides for strong acid hydrolysis of plant biomass con sisting largely of cellulosic and hemicellulosic materials. See US. Pat. No. 5,526,777 (’777 patent), entitled “Method
situations Where the biomass has increasing amounts of hemicellulose, the entire range of C6 and C5 sugars is
produced. The present invention discloses a novel method to pro
duce dehydration products of sugars, such as levulinic acid 10
of Producing Sugars Using Strong Acid Hydrolysis of Cellulosic and Hemicellulosic Materials,” and hereby incor porated by this reference thereto. This acid hydrolysis
sugars. The present invention also alloWs for the selection of conditions that can alter the product ratio so that economic
method results in a high yield of sugars as an intermediate
in the process. Moreover, this acid hydrolysis process pro
(LA), furfural, 5-hydroxymethyl-2-furanone (5-HMF), maleic acid (MA), succinic acid (SA), and fumaric acid (FA), even if the starting components consist of mixed
15
?exibility can be incorporated into the production of these
vides a means for producing sugars from biomass in a manner that reduces the amount of Waste product of effluents
dehydration products.
produced.
vides steps to prepare high yields of the dehydration prod
In addition, the method of the disclosed invention pro
ucts and to prepare the products that all process streams are Thus, the process of the ’777 patent is designed to reuse all aqueous streams and to convert all solids to saleable or 20 reusable, after the recovery of the desired products.
useful products. Much of the acid used is also recovered for recycling. Also Where the biomass contains high levels of silica, the process is able to produce silica gel, sodium
Moreover, the present invention alloWs for these dehydra
tion products to be produced in high yield in economically viable and environmentally safe processes. Finally, the invention also discloses the method of preparation of deriva
silicate, potassium silicate, Zeolites, or other ancillary prod ucts. Moreover, a high yield of sugar is obtained form the
25
There are numerous advantages to the present invention.
sugar streams unnecessary for most subsequent processes.
Other features of the patented acid hydrolysis method contribute to its efficiency and economic feasibility in the production of sugars. These include the use of atmospheric pressure and relatively loW temperatures. Moreover, the process does not involve the production of furfural and similar undesirable byproducts Which are toxic and also may inhibit subsequent reactions of the sugars thus obtained. Finally, this process does not require the use of exotic and expensive materials of construction such as tantalum steel. Thus, the process of the ’777 patent provides an efficient, cost-effective means of producing useful chemicals from the hydrolysis of agricultural Waste, While at the same time
These include the folloWing: 1. A mixed C6—C5 acid stream can be used Without the 30
need for separating the sugars; 2. The yields of levulinic acid and its derivative, MTHF, are signi?cantly higher than other knoWn methods, in part due to the high concentration of sulfuric acid Which Was discovered to act as a dehydration catalyst
35
at the concentrations utiliZed in the present invention; 3. The concentration of sulfuric acid remains high
throughout the reaction and subsequent separation, thus
producing little or not Waste ef?uents or materials. 40
facilitating its recovery for reuse; 4. The product mix can include products Which become intermediates to the common ?nal product; 5. The invention alloWs for the recycle and reuse of all streams, and any unWanted byproducts can be subse quently oxidiZed to non-toxic materials.
Moreover, since the hydrolysis process produces a high yield of sugars, it Would appear to be a suitable method for use in the production of useful derivatives from the sugar intermediate thus obtained. One such derivative could be levulinic acid.
tives of levulinic acid by hydrogenation yielding methyltet
rahydrofuran (MTHF).
hydrolysis of the biomass, making concentration of the
45
This last advantageous aspect of the invention is signi?
The present invention provides an improved process for
cant When sulfuric acid is used in the process because the
obtaining levulinic acid from sugar, as Well as derivatives of
presence of this acid Will degrade and oxidiZe products if not
levulinic acid, such as methyltetrahydrofuran(MTHF).
removed. For example, HZSO4 degrades formic acid, Which
Levulinic acid can be produced from sugars derived from cellulose and hemicellulosic materials, as detailed in ’777
is formed as a necessary by-product in the dehydration reactions. FIG. 1 shoWs a Product FloW Diagram indicating the
patent and incorporated herein by reference, or from sugars
overall steps leading to the production of levulinic acid and/or MTHF. This Product FloW Diagram is illustrative of
derived from other sources. It should be noted, hoWever, that
although the strong acid hydrolysis process described in the ’777 patent, provides an efficient means of producing sugars from biomass to be used subsequently in the method of the present invention, this method represents only one route to
a preferred embodiment. All streams are indicated by arroWs 55
Which the product streams are directed. First the sugar (1) is feed into the reactor The sugar can be derived from the process of strong acid hydrolysis, as
obtain raW sugar to be used as starting material in the
disclosed invention. The novel method of the present inven tion leading to levulinic acid can utiliZe any sugar compo nent as a starting material, regardless of Whether the sugar is mixed, a combination of 5-carbon and 6-carbon sugars, or exclusively contains 5-carbon or 6-carbon sugars. If the method detailed in the ’777 patent is utiliZed to
obtain sugar, the hydrolysate Will generally include the 6-carbon sugars (C6) glucose, mannose and galactose and the 5 -carbon sugars (C5) xylose and arabinose. The hydroly sate mixtures formed in the method of the ’777 patent
With the overall steps being illustrated by the larger boxes to
detailed in the ’777 patent, or can be any sugar, either a 60
mixed sugar, consisting of both 6-carbon and 5-carbon sugars, or exclusively a 6-carbon or 5-carbon sugar. Next the
reaction mixture is heated at 80°—120° C. for 7 to 42 hours.
Preferably the reaction of the sugars in concentrated sulfuric acid is carried out at 100° C. for 24 hrs. When the method 65
detailed in the ’777 patent is used, the concentration of sulfuric acid Will be in the range of 25—39%, Without further addition of acid. If the sugar source is not from that of the
5,892,107 7
8
strong acid hydrolysis method, however, sulfuric acid is
hydrolysis process. Furfural (18), along With 5-HMF, can also be separated by the chromatography method described above, eluting from the column after the sulfuric acid component of the reaction mixture. The furfural containing
added to the reactor to a ?nal concentration of approxi
mately 30—39%. Next the resulting product mixture (3) is transferred to a ?ltration system (4), Where an initial cake (5) is formed. The ?rst ?ltrate (6) is then transferred to the holding tank The cake is subsequently Washed With H20 (8), resulting in a second ?ltrate (9) Which is also transferred to the holding tank. After the H20 Wash, the cake discharge (10) can be removed from the ?lter. The combined ?ltrates (11) are then applied to the chro matographic separator (12), Where the products of the reac
eluent can then be further concentrated and puri?ed (19),
leading to furfural product (20) and H20 (21). The ?nal eluent from the chromatographic separator is levulinic acid (22) in H2O With a small amount of acid. The
product can be further concentrated (23) by evaporation of 10
are separated by H20 (13) feed into the separator. Preferably 15
One use of the levulinic acid obtained is to hydrogenate the product to MTHF. If MTHF is desired as an end product, angelica lactone isomers are transferred to the hydrogenator
referred to in the art as “simulated moving bed chromatography,” can be utiliZed to effect the initial sepa 20
recycles betWeen columns. FIG. 2 shoWs a typical chromatograph of the separation after reaction for 24 hrs at 100° C., Where levulinic acid is
at 50° C. to at temperature beloW the decomposition tem 25
vided prepacked With a Weak anion amine resin and is available from Rainin of Woburn, Mass. As FIG. 2
illustrates, sulfuric acid can be cleanly separated from the levulinic acid product. This alloWs the strong acid to be recycled for reuse, and thus, adding to the economic viabil ity of the process. Under these conditions, succinic, maleic and fumaric acid can also be separated. The folloWing sets forth one exemplary set of speci?c
separation conditions:
perature of the lactone, Which is approximately at 200° C. The product, MTHF (30), can then be transferred to a liquid or vapor phase dryer unit to remove H20 (31), also making using of a desiccant or absorbent. The ?nal MTHF product
is noW in a dry blend form (32). Moreover, the production 30
of a mixed stream in this case, that is MTHF and ethanol, Would have an advantage over current technology in the ?nished mixtures can be made more economically than
making the products separately, and then blending the ?n 35
A 24“ long, 2“ in diameter column Was loaded With Mitsubishi A306S anionic resin to a bed volume of 1 liter.
75 ml of levulinic acid/sulfuric acid mixture (5% levulinic acid and 30% H2504) Was fed onto the column and eluted With H2O. Levulinic acid eluted from the column after approximately 24.5 minutes With the sulfuric acid eluting at approximately 28 minutes. With an application of only 50 ml, the levulinic acid still eluted at approximately 24.5 minutes, While the sulfuric acid eluted at approximately 29.75 minutes. It is important that these separation condition yield enough of a difference in the elution pro?le of the
(26), along With H2 (27), ethanol (28), and the Ni/Co catalyst (29). This mixture is reacted in the hydrogenation reactor at a pressure of 750—3000 psig, until there is no remaining H2 uptake. Preferably, the temperature of the reaction Would be
the removal of products, addition of further eluents, or
the primary product. This chromatograph Was generated using a DynamaxTM NH2 83-701-C column, Which is pro
vacuum is applied at 10 torr. Thus, various forms of isomers of angelica lactone (25) can be formed, Which can be
collected and used in the hydrogenation reaction.
preferably, a system of multiple chromatographic columns, ration; the use of multiple chromatographic columns permits
levulinic acid product containing a small amount of acid. Advantageously, the acid present serves as a catalyst, thus
obviating the need to add acid at this point. Once the H20 is removed, the temperature is increased to 150° C., and a
tion as Well as sulfuric acid can be separated. The products
the resin utiliZed in the chromatography is an anionic resin, for Which sulfate ions form the anionic state. Most
H20 (24) prior to the hydrogenation reaction, leaving
40
ished products for use. It should also be noted that in many instances it is more economically sound to insert an separation step in the midst of the levulinic formation at the site of the primary reactor, so that product of value can be immediately extracted. Thus, it may be undesirable to Wait 7—42 hours to extract the
products. For example, in this dehydration reaction, as time proceeds furfural is converted into succinic, maleic, and fumaric acids. If furfural Was a desired product, it Would be
preferred to do an initial separation early in the reaction, and then, sending the remainder back to the reactor for comple 45
tion of the levulinic acid reaction.
It is noteWorthy that the dehydration reaction produces
products to be utiliZed on a moving bed commercial chro
different products as the time of reaction is increased. At
matographic separation system. Moreover, it appears that
100° C., the reaction of the 6-carbon sugars Will go through 5-HMF yielding levulinic acid, Whereas the reaction of 5-carbon sugars Will go through furfural to yield succinic, maleic, and fumaric acids. HoWever, literature in the art
the separation can proceed using a cationic resin as Well.
Another example of a particular separation procedure is as
50
folloWs: A 24“ long, 2“ in diameter column Was loaded with Bow XFS-43254.00 anion resin to a bed volume of 1 liter. 100 ml
indicate that these reactions may not be exclusive, in that a
of levulinic acid/sulfuric acid (5% levulinic acid and 30% HZSO4 Was fed to the column and eluted With H2O. Levulinic acid eluted at approximately 22.75 minutes, and the sulfuric acid eluted at approximately 40 minutes. In this example, there Was total separation, With no overlap of the peaks, thus indicating that this procedure could be used to
55
give an effective separation even in the absence of simulated
60
moving bed techniques. HoWever, the moving bed chro
intermediate product of the reaction With 6-carbon sugars may be a 5-carbon sugar production, and vice versus. Ojota et al. J. Pharm. Pharmaa, 301668 (1978). In addition, Great Lakes Chemical have a chemical process of making MTHF
from furfural alcohol, by starting With 5-carbon sugars and resulting in furfural. Moreover, it is generally hypothesiZed that the synthesis of levulinic acid requires the simultaneous oxidation of aldehydes, as a source of hydrogen, resulting a reduced form of levulinic acid. Thus, if mixed sugars are used in the
matographic techniques are preferred because higher con centrations could be maintained throughout the separation.
reaction, the overall yields can be improved because the
FolloWing the chromatographic separation, sulfuric acid
removal of H20 (16) and concentrated HZSO4 (17) being
degradation products of the 5-carbon sugars, for example, the aldehydes produced, act as appropriate reducing agents for the reaction, leading to higher yields of levurinic acid
available for reuse at the initial stage of the strong acid
from the 6-carbon sugars.
(14) is feed into an acid concentrator (15) leading to the
65
5,892,107 9
10
Although it is possible to Write a balanced equation for the
leading to the desired product(s), the products can be sepa rated from the acid component via chromatography, as described in the above Product FloW Diagram. The advantage of proceeding via this route is that the
reaction of a 6-carbon sugar leading to one mole of levulinic
acid, one mole of formic acid, and one mole of H20, the actual reaction mechanism is not completely knoWn. The
strong acid hydrolysis method produces sugars in high
requirement of a saturated levulinic acid product, plus the unsaturated nature of 5-HMF, hoWever, indicate that it is highly probable that more than one mole of 6-carbon sugar is required to yield a mole of levulinic acid. For example,
yields in a convenient part of the raW material concentration
scheme, as described in the ’777 patent. Another advantage is that reactions can be carried out With only minimal
puri?cation of intermediates products. Thus, ?nal puri?ca
Augh et al. shoWed polymeriZation of 5 -HMF, thus reducing levulinic acid. Thus, the theoretical yield of 64% dictated by
10
the simple balanced equation is never achieved. The reported yields are generally on the order of 20% of the theoretical yield, ie a yield of about 13%. There are only a feW reported results; in one report, 150 g of product resulted from reaction of 1000 g of glucose With HCl, ie a 15%
15
yield. This result Was claimed to be an improvement over
glucose, by Weight, Was reacted in the presence of 1%, by
previous reported results. See Sah et al., supra. In the present invention the actual yield of levulinic acid
Weight, for 24 hours at 100° C., as described in the literature. See P. T. Sah and S. Y. Ma, “Levulinic Acid And Its Esters,”
for the 7 hour reaction time Was 23.3%, or 36% of the
theoretical yield. This yield is approximately 50% higher
tion can be done later in the regime after products of high value have been obtained. It Was also discovered by experimentation that sulfuric acid does not proceed via same the mechanism as HCl, Which is the acid generally used in the art to produce dehydration products of sugars, such as levulinic acid. An original experiment Was performed Where a solution of 10%
20
J. Amer. Chem. Soc., 52, 4880 (1930); L. Fieser and M.
than the reported literature value. See L. Fieser and M.
Fieser, “Reagents for Organic Synthesis,” John Wiley and
Fieser, “Reagents for Organic Synthesis,” John Wiley and
Sons, Inc. 1967, p. 564—66. After essentially folloWing
Sons, Inc. 1967, p. 564—66. It is noteWorthy that the 24 hour
literature reaction conditions, except that HZSO4 Was used instead of HCl, there Was virtually no sugar degradation and no production of levulinic acid.
reaction yields approximately tWice the reported yields. Finally, analysis of the method of the present invention,
25
indicate that all the sugar disappears from the reaction mixture betWeen 7—24 hours after the reaction is initiated.
A similar reaction Was also performed in Which a solution
of 3% HZSO4 and 10% glucose Was reacted at 100° C. for 24 hours. In this case, the glucose decreased to 7.34% With
These results also shoW an increase in 5-HMF as a function
a signi?cant production of 5-HMF, but only insigni?cant
of decrease of the sugar levels in the reaction mixture.
Levulinic acid is produced following the appearance of
30
Was produced, in sharp contrast to the reported yields in the presence of HCl. It should be noted that in substituting H2SO4 for HCl, the difference in acidic value of each acid
5-HMF. A Method of Production of Levulinic Acid and other Dehy
dration Products of Sugars Derived From Strong Acid
Hydrolysis A method of strong acid hydrolysis of cellulose and
Was taken into consideration. Thus, a 6% solution of HCl is 35
hemicellulose is detailed in the ’777 patent. This is a preferred method to derive sugars as starting material for the production of levulinic acid and its derivatives, as disclosed
in the present invention. In the folloWing examples, the hydrolysate Was generally derived from rice straW. In
40
addition, to present examples that illustrate the reaction under varying conditions, 5 -carbon and 6-carbon sugar Were added to modify the ratio present in the hydrolysate. After the conventional hydrolysis step of the ’777 patent, there are tWo points in this process Where chemistry can be
The tWo points in the acid hydrolysis process Where additional chemistry can be performed are: 1) immediately after the belt pressing step (See FIG. 1 of the ’777 patent) or
approximately equivalent to a 3% solution of H2SO4. These unanticipated results indicate that the mechanism of acid action is different With HZSO4 rather than HCl. Moreover, these surprising data lend support to use of the hydrolysate generated in the strong acid hydrolysis method of the ’777 patent. The advantage of using this hydrolysate are many. It is produced at high concentrations in the ?rst part of the ’777 method, it contains high concentrations of HZSO4 Which are necessary to get signi?cant quantities of levulinic acid, or
other dehydration products, and ?nally, puri?cation steps are 45
performed. Moreover, either the mixed sugar stream, Which is the ?rst hydrolysis stream, or the second hydrolysis stream consisting of virtually all glucose can be selected for use in subsequent chemical reactions. (See FIG. 1 of the ’777 patent). Of course, these tWo streams can be combined yielding mixed sugars as starting material in further reac tions.
amounts of levulinic acid. Here 0.058% of levulinic acid
eliminated until the desired products are obtained. EXAMPLE 1 Production of Levulinic Acid
50
A mixture of 5-carbon sugars, primarily xylose, 6-carbon sugars, primarily glucose, and HZSO4 Were reacted in H2O. The concentration of mixed sugars Was 10—22%, by Weight, the inorganic acid Was 25—39% by Weight, With the remain der being H2O. This sugar mixture Was prepared by the
strong acid hydrolysis method by: 55
1) mixing materials cellulose and hemicellulose With a
sulfuric acid is removed from the sugar residue (See FIG. 2
solution of approximately 25—90% of H2SO4, by Weight, thereby at least partially decrystalliZing the
of the ’777 patent).
biomass and forming a gel that includes a solid and
2) immediately after the acid/sugar separator step, Where
liquid portion;
After Pressing After the pressing step, Which folloWs the ?rst hydrolysis step, the sugar concentration is approximately 15%, While the acid concentration is approximately 30%. It is this stage
60
of approximately 20—30% by Weight and heating the gel to about 80°—100° C., thereby hydrolyZing the cellulose and hemicellulose materials (?rst hydrolysis
of the strong acid hydrolysis process that appears to be ideal
for optimiZation of dehydration reactions leading to levulinic acid, furfural, 5-HMF, and other degradation prod ucts of these primary products, succinic, maleic and fumaric acids. FolloWing the reaction of the sugar/acid mixture,
2) diluting the gel thus obtained to an acid concentration
step); 65
3) separating the liquid portion from the solid portion, thereby obtaining a ?rst liquid containing a sugar/acid
mixture;
5,892,107 11
12 80°—100° C., thereby further hydrolyZing the cellulose and hemicellulose materials remaining in the separated
4) mixing the separated solid portion With a solution of about 25—90% HZSO4 by Weight until the acid concen tration of the resulting gel is betWeen 20—30%, by Weight, and then heating the mixture to temperature of 80°—100° C., thereby further hydrolyZing the cellulose and hemicellulose materials remaining in the separated
solid portion (second hydrolysis step); 5) separating the resultant liquid portion from the solid portion thereby obtaining a second liquid containing a
sugar/acid mixture;
solid portion (second hydrolysis step); 5) separating the resultant liquid portion form the solid portion, and thereby obtaining a second liquid contain ing a sugars/acid mixture; 6) combining the ?rst and second liquids. The above liquid mixture is then heated at approximately 80°—120° C. for about 7—42 hours, depending on the product ratio desired. It is preferable, hoWever, that the reaction
temperature be approximately 100° C. The dehydration products formed are levulinic acid, 5-HMF, furfural, suc cinic acid, maleic acid, and fumaric acid. The product stream is then separated into component liquid streams containing the desired combination of products, or the individual products, and a separate stream Which contain the inorganic acid, as illustrated in the Prod uct FloW Diagram. The organic product streams each con tain less that 3% sulfuric acid, and the inorganic stream contains less than 3% organic product. The inorganic stream
6) heating this second liquid mixture at a temperature of approximately 80°—120° C. for about 7—42 hours, depending on the desired product ratio, thereby form 10
ing primarily levulinic acid, 5-HMF, furfural, succinic acid, maleic acid, and fumaric acid;
7) separating this resulting third liquid, containing 15
levulinic acid, 5-HMF, furfural, succinic acid, maleic acid, and fumaric acid, from the solid portion. 8) treating the ?rst liquid stream With heat at approxi mately 80°—120° C., preferably at 100° C., for about 7—24 hours, depending on the desired product ratio; 9) the reaction mixture noW contains levulinic acid,
20
5-HMF, furfural, succinic acid, maleic acid, and fumaric acid, Which is then combined With the third
liquid containing the similar products thereby forming a single product stream; 10) the resultant product stream is then separated into
can be concentrated to facilitate reuse of the sulfuric acid. 25
component liquid streams containing the desired com binations of products or the individual components, and a separate stream containing sulfuric acid, as detailed in the above Product FloW Diagram;
The organic products are further puri?ed by conventional means resulting in the removal of H20, inorganic acid and minor impurities. For example, furfural is puri?ed by a second distillation, Which folloWs aZeotropic distillation of
11) the organic products are concentrated by removal of
the furfural/H2O mixture. Levulinic acid can be further
H20, and puri?ed to remove residual inorganic acid
puri?ed by ?rst by distilling the product folloWed by
and minor impurities by adjusting the pH With lime, in the case of HZSO4 removing S042 ions.
vacuum distillation. If necessary, recrystalliZation of the
levulinic acid product can also be performed. EXAMPLE 2 Production of Levulinic Acid
35
A mixture of 5-carbon sugars, primarily xylose, 6-carbon sugars, primarily glucose, and HZSO4 Were reacted in H2O.
Which a solution of levulinic acid is ?rst prepared by mixing material containing cellulose With a solution of sulfuric acid
The reaction conditions consist of heating the mixture at a
temperature of 80°—120° C. for 7—42 hours, depending on
40
the desired product ratio of levulinic acid, 5-HMF, furfural, maleic acid, succinic acid and fumaric acid. Preferably the reaction Would proceed at 100° C. for 24 hrs. The concen
tration of mixed sugars Were 10—22%, by Weight, the inorganic acid Was 25—39% by Weight, With the remainder
45
being H2O. After production of the dehydration products, prepared by the strong acid hydrolysis method by: 1) mixing materials containing cellulose and hemicellu
HZSO4 by Weight, thereby at least partially decrystal
?nal liquid portion folloWing the reaction.
liZing the biomass and forming a gel that includes a 55
of approximately 20—30% by Weight and heating the gel to about 80°—100° C., thereby hydrolyZing the cellulose and hemicellulose materials (?rst hydrolysis
step);
The product stream is then separated into component liquid streams containing the desired combination of products, or the individual components. The inorganic acid is contained in a separate stream. Final puri?cation of the
organic products is performed as outlined in the above Product FloW Diagram. 60
3) separating the liquid portion from the solid portion,
EXAMPLE 4
thereby obtaining a ?rst liquid containing a sugar/acid
mixture; 4) mixing the separated solid portion With a solution of about 25—90% HZSO4 by Weight until the acid concen tration of the resulting gel is betWeen 20—30% by Weight, and then heating the mixture to temperature of
heated to a temperature betWeen 80°—100° C. for a time
the desired product ratio. TWo portions again form: a liquid portion and a solid portion. The primary product of this reaction, hoWever, is levulinic acid, Which is contained in the
lose With a solution of approximately 25—90% of
2) diluting the gel thus obtained to an acid concentration
that is 25—90% acid by Weight. This initial step alloWs for partial decrystalliZation of the cellulosic materials. A gel is then formed that includes a liquid and solid portion. Next the gel is diluted to yield an sulfuric acid concentration of about 20—30% by Weight. The gel is then interval of 45 minutes to 2 hours. This step hydrolyses the cellulose. The liquid is further heated at temperature ranging from 80°—120° C. for approximately 7—42 hours, depending on
the reaction mixture is separated and puri?ed as described in the Product FloW Diagram of FIG. 1. This mixture Was
solid and liquid portion;
EXAMPLE 3 Production of Levulinic Acid In this example, the raW materials consist of only cellu lose. This example is a modi?cation of examples 1 and 2 in
65
Production of Levulinic Acid 700 grams of hydrolysate solution obtained from strong acid hydrolysis method detailed in example 1, Which contained 15.5% sugars, mostly consisting of glucose, Was heated for various times at 100° C. After seven hours, the reaction mixture contained 3.95% of levulinic acid.
5,892,107 14
13
butylated hydroxytoluene. In the disclosed hydrogenation
EXAMPLE 5 Production of Levulinic Acid
reaction, inclusion of ethanol in the reaction, greatly reduces
120 gallons of hydrolysate from strong acid hydrolysis process, as described in example 1, containing approxi mately 1% by Weight of glucose and residual degradation products of xylose, Was placed in an acid concentrator to remove the residual H20 and concentrate the acid. After reacting at 100° C. for 24 hours, the reaction mixture Was found to contain 0.3% levulinic acid. This example demon strates the feasibility of producing levulinic acid as part of
the risk of explosion associated With the production and use
of MTHF product. Additionally, by the inclusion of ethanol in the entire process, including drying of the product, the risk of explosion further reduced. The mixture is reacted With H2 in the reactor in the presence of a suitable catalyst, preferably a Co/Ni catalyst. Hydrogen is added at an excess pressure of 750—3000 psig 10
the routine acid recovery step in the strong acid hydrolysis process, given that the solution contains residual sugar.
until there is no further H2 uptake. Any residual H2O is removed by aZeotropic distillation or molecular sieve dry ing. The resulting product is an ethanol-MTHF blend Which
is ready for use or can be further separated into its tWo EXAMPLE 6 components. Production of Esters of Levulinic Acid 15 It should be noted that although furfural can be hydroge It is possible to recover levulinic acid esters directly from nated in the presence of a Ni/Co catalyst, it is more difficult the completed reaction as described in example 1. In this to hydrogenate than 5-HMF or 5-M-2-F. Thus, at the con
case, excess methyl or ethyl alcohol, that is, in stoichiomet
ditions speci?ed for hydrogenation reaction of levulinic acid in the present invention, the entire mixture Will be hydro genated to yield MTHF. Moreover, the conditions for pro ducing MTHF need to be selected for optimiZation of the
ric excess to the amount of levulinic acid produced after the
reactor step (see Product FloW Diagram), can be added to the levulinic acid/sulfuric acid mixture. The resulting mixture is re?uxed for 3 hours forming the ester. The excess alcohol can then be distilled off the levulinate product. The levuli nate ester can be recovered by phase separation, since it forms an oily layer atop of the aqueous layer. The ester product can also be separated from the sulfuric acid
reaction. If too much hydrogen pressure, or too high a temperature, is used, the reaction may go pass MTHF to
component, as Well as from the excess alcohol, by the
Production of MTHF
separation methods used for the levulinic acid product
The process of Example 7 is performed With the addition of dry ethanol rather than aqueous ethanol.
yield 1,4-pentanediol instead. EXAMPLE 8
described above.
The folloWing is example leading to the production of levulinate ester:
30
368 grams of a completed reaction solution from hydroly sate Was used to form levulinate ester. In this case, the
the hydrogenation reactor. In this example, the hydrogen
solution contained approximately 15.5 grams of levulinic acid and 110 grams of H2SO4. Next ethanol Was added in excess. The resulting mixture Was heated to ethanol re?ux,
pressure in the hydrogenation step is increased to approxi 35
approximately 80° C., for 3 hours. FolloWing removal of the
remaining concentration of acid is approximately 1%. This 40
EXAMPLE 7
Production of MTHF
acid can either be left in the sugar mixture, or the acid can be converted to a salt Which may be a suitable catalyst for
the next chemical conversion, depending on the chemical
After the dehydration reaction of heating the sugars in concentrated sulfuric acid, as detailed example 1, the reac tion mixture is then ready to be separated as illustrated in the
mately 2000—5000 psig. After Sugar/Acid Separation After the sugar and acid have been separated, Which can be done after the ?rst hydrolysis step, or after the second, the
HZSO4 by chromatography, and removal of the remaining ethanol by distillation, approximately 15 grams of levulinate ester Was recovered.
EXAMPLE 9 Production of MTHF The process of Example 7 in Which no ethanol is added to
route chosen. 45
Product FloW Diagram. The chromatographic separation is
Examples of additional chemical reactions that can be accomplished on the sugars after separation from the inor
of levulinic acid, furfural and 5-HMF in a common aqueous
ganic acid component include: 1) neutraliZation of the acid With sodium sulfate folloWed by electrolytic reduction to polyols; 2) air oxidation in the presence of sulfuric acid leading to difunctional acidic sugars; 3) neutraliZation of the sugar/acid mixture to a pH of 9.5—10.0 folloWed by air
solution. This aqueous solution is then concentrated by
oxidation to monofunctional acidic sugars.
removal of H20.
In is important that in both experimental approaches, either using the hydrolysate immediately after pressing, or
controlled to remove the sulfuric acid, and any of the
succinic, maleic and fumaric acids that are produced in the
dehydration reaction, While leaving the remaining products
Next the mixture is heated at approximately 150°—175° C.
by ?rst putting the hydrolysate through the acid/sugar sepa
under a vacuum of 1—50 mm Hg, Which converts the
levulinic acid to 5 -methyl-2-furanone (5-M-2-F). The result
55
ing mixture, containing 5-M-2-F, furfural, and 5-HMF into the hydrogenation reactor. Additionally, an ethanol solution in Water, approximately 70—95% ethanol, is added to the hydrogenator reactor Water/ethanol is frequently used in hydrogenation reactions. In this example, the interaction of the MTHF product With ethanol alloW for more facile drying and provides the product blended With solvent. The main reason, hoWever, for the inclusion of ethanol in the hydro genation reaction is that the MTHF product is highly ?am
mable and knoWn to produce explosive peroxides. This high
ration process, the critical puri?cations Would be delayed until the value of the desired products are at their highest value for recovery. Thus, puri?cation can be delayed until the production of the ?nal products. If needed, an initial separation and puri?cation of ?nal products can be accom
60
plished by the separation method described in the Product FloW Diagram of FIG. 1. Final puri?cations steps can be achieved in the conventional manner.
Exemplary Methods of Production of Levulinic Acid from
Sugars 65
The folloWing examples set forth speci?c techniques of
volatile nature of MTHF does not generally permit it to be
the production of levulinic acid from different sugar mix
used or shipped Without the addition of an inhibitor, such as
tures:
5,892,107 15
16
EXAMPLE 10
The ZrOZ/CuOAc Was dried for 4 hours at 105° C. The mixture Was then placed in a kiln and heated up to 850° C., Where it Was held at this temperature for 30 minutes. The purpose of the heating step above is to convert the acetate salts to oxides Which become bound to the substrate
The solution of 3% xylose, 12% glucose and 30% sulfuric acid Was heated for various times at 100° C. The quantity of the total reactants Was 500 grams. After 7 hours there Was no
sugar left and the levulinic acid concentration Was 1.1%. By 16 hours, the levulinic acid had increased to 2.6%; and at 24 hours, the levulinic acid concentration Was 4.2%. The ?nal absolute yield of levulinic acid Was 35% or 54% of the
theoretical yield. EXAMPLE 11
10
A solution of 12% glucose, by Weight, and 30% H2504,
making a reaction mixture comprising said one or more sugars, Water and sulfuric acid , Wherein said sulfuric
approximately 2.33%, and the sugar Was reduced only
20
25
these substrates can be impure, thus the highest grade metal substrate is not required for the production of the hydroge
nation catalyst. If using a salt of any of the transition metal catalysts, these
tivated by the cooling process, they can be regenerated by
35
40
reheating at 850°—1000° C.
hydrogen pressure Which Will optimiZe the yield of MTHF Without conversion of signi?cant quantities of MTHF to 1,4-pentanediol. The other major constraint is temperature at
14. The method of claim 1, Wherein step of separating the 15. The method of claim 1, Wherein the step of separating
the products comprises chromatography using an anionic resin.
reactor temperature does not exceed 2000 C.
16. The method of claim 1, Wherein the step of separating
the products comprises chromatography using a multiple chromatographic columns.
EXAMPLE 12 55
separating the reaction products; and
recovering methyltetrahydrofuran. 60
and 80 grams of ZrO2 of roughly 1/14“ spheres Was added.
18. The method of claim 17, Wherein ethanol is added
during the hydrogenation step.
ture for 30 minutes, cooled and removed for use. EXAMPLE 13
17. The method of claim 1, additionally comprising: hydrogenation of levulinic acid thus obtained in the presence of H2 and a metal catalyst;
grams of Ni or C0 acetate Was dissolved in 40—50 ml of
1 gram of copper acetate Was placed in 40 ml of ethanol
13. The method of claim 1, Wherein the step of separating
the products comprises chromatography. products comprises chromatography using an ionic resin.
radation of both starting products and lead to degradation of the desired end product. Generally it is preferred that the
ethanol or methanol. 80—100 grams of roughly spherical alumina or Zirconia particles of approximate diameter of 1/14“ diameter Were placed in the liquid, removed, and dried for about 4 hours at 105° C. The particles Were then placed in a kiln, Which is heated to 850° C. (this heating step took 1.5 hours). The pellets Were held at, or above, this tempera
comprises 30—40% of said reaction mixture by Weight. 12. The method of claim 1, additionally comprising acid.
45
the hydrogenation step. Excess temperatures can cause deg
As an example of the preparation of a catalyst for the hydrogenation reaction of levulinic acid to MTHF, 1—15
6. The method of claim 1, Wherein said sugars are derived from cellulosic and hemicellulosic materials. 7. The method of claim 1, Where the reaction temperature is at 80°—200° C. 8. The method of claim 1, Where the reaction temperature is at 90°—120° C. 9. The method of claim 1, Where the reaction time is betWeen 4—48 hours. 10. The method of claim 1, Where the reaction time is betWeen 7—36 hours. 11. The method of claim 1, Where the sulfuric acid
recovering a product selected from the group consisting of furfural, 5-HMF, succinic acid, maleic acid and fumaric
For each catalyst particle siZe, surface concentration of metal oxide species, ratio of catalyst used to reactor siZe, reactor volumes and temperatures, there Will be a speci?c
carbon sugars. 4. The method of claim 1, Wherein said comprises a mixture of 5-carbon and 6-carbon sugar. 5. The method of claim 1, Wherein said sugars are derived
from plant biomass.
(A1203), magnesia (MgO) or Zirconia (ZrOZ). Moreover,
is also immersed in the solution, and then, removed and dried. This dried matrix, containing both the catalyst and substrate, is then placed in a kiln, and heated to 850°—1000° C., for at least 30 minutes, folloWed by cooling before use in the hydrogenation reaction. If the catalysts become deac
hours to produce dehydration products; separating the sulfuric acid from said dehydration prod ucts; and recovering levulinic acid. 2. The method of claim 1, Wherein said sugar comprises only 6-carbon sugars. 3. The method of claim 1, Wherein said comprises only 5
Cu, Mn, Co, or Ni. Preferably, a mixture of Ni/Co can be used as the catalyst for hydrogenation of levulinic acid. The substrates for the catalyst can be chosen form alumina
salts can be dissolved in ethanol or methanol. The substrate
Weight: reacting said reaction mixture at 40°—240° C. for 1 to 96
sugar left, and the levulinic acid Was noW at 2.95%, or 46%
of the theoretical yield Hydrogenation Reaction Leading to MTHF: Preparation of the Metal Catalyst Atypical hydrogenation catalyst can be prepared from Fe,
acid comprises 20—80% of said reaction mixture by
15
a 7 hour reaction time, levulinic acid production Was
slightly further. After 24 hours, there Was not measurable
1. A method of producing levulinic acid from one or more
5-carbon or 6-carbon sugars comprising:
by Weight, Was heated for various times at 100° C.:5° C. After 3 hours no signi?cant levulinic acid Was formed,
hoWever, the sugar had degraded to 4.49% along With signi?cant production of 5 -HMF. After 4 hours, the levulinic acid production Was only 0.18% While the sugar had been reduced by approximately one-half of the 3 hour point. After
surface. The acetate salts form only CO2, and Water upon heating. HoWever, although nitrate salts can be used for this process, these salts form toxic NO2 instead upon decomposition, and thus, are less preferred. What is claimed is:
65
19. The method of claim 17, Wherein the methyltetrahy drofuran is dried after the hydrogenation reaction, leaving a methyltetrahydrofuran product in a dry blend form. 20. The method of claim 17, Wherein dry ethanol is added. 21. The method of claim 17, Wherein the metal catalyst is
Ni/Co catalyst.
5,892,107 17 22. The method of either claim 1, additionally comprising dehydration of levulinic acid to yield a product comprising an angelica lactone.
23. The method of claim 1, additionally comprising ?ltering the reaction products prior to separation. 24. The method of claim 23, Wherein the ?lter is Washed
With H20. 25. The method of claim 24, Wherein both the ?rst ?ltrate and second ?ltrate folloWing the H20 Wash are combined
before separation. 26. The method of claim 1, Wherein levulinic acid is concentrated after separation and recovery. 27. The method of claim 1, additionally comprising: adding an alcohol to the levulinic acid;
re?uxing at the temperature of the alcohol for 1—10 hours;
18 separating the mixture; recovering levulinate ester. 28. The method of claim 27, Wherein the reaction mixture is re?uxed at the re?ux temperature of the alcohol for 2—8 hours. 29. The method of claim 27, Wherein the reaction mixture is re?uxed at the re?ux temperature of the alcohol for 3—6 hours. 30. The method of claim 1, Where the sulfuric is not neutraliZed. 31. The method of claim 1, Where said one or more sugars
comprises 10—22% of said reaction mixture by Weight. 32. The method of claim 1, Where said one or more sugars
is obtained from hydrolysis of cellulose by sulfuric acid Wherein the ratio of sulfuric acid to cellulose is 1:1 to 1.25:1
by Weight.
UNITED STATES PATENT AND TRADEMARK OFFICE
CERTIFICATE OF CORRECTION 5,892,107
PATENT NO.
;
DATED
; April 6, 1999
'NVENTOR(S) : William A. Farone, et al. It is certi?ed that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:
Column 16, Line 23, “said comprises” should be changed to “said sugar comprises” Column 16, Line 25, “said comprises” should be changed to “said sugar comprises”
Column 16, Line 47, “wherein step” should be changed to “wherein the step” Column 17, Line 1, "The method of either claim 1” should be changed to "The method of claim 1”
Column 18, Line 9, “ where the sulfuric is” should be changed to “where the sulfuric acid is”
Signed and Sealed this Fifteenth Day of August, 2000
Q. TODD DICKINSON
Arresting O?icer
Dirumr of Patterns and Trademark:
